Bright Mild Steel Bar

Bright steel bars are carbon steel which has had the surface condition improved over the hot rolled finish supplied by the steel mill. Advantages achieved include improved machinability, enhancement of physical and mechanical properties and improved dimensional tolerances and straightness.

Cold finished steels are covered by Australian Standard AS1443.

Types of cold finished bars

Cold drawn bars are widely used in mass production of parts due to their excellent mechanical and dimensional properties, with machinability in excess of the hot rolled condition. Round, hexagonal and square bars can be produced by cold drawing.

Turned and polished round bars have similar mechanical properties to those of equivalent hot rolled bar, but exhibit a smooth, bright surface finish and improved dimensional accuracy. They are widely used where a surface free of decarburisation is required, for example in induction hardening and when the surface must be free from surface defects, such as for use in cold forming.

Cold drawn and precision ground or turned and precision ground round bars, where very close dimensional tolerances and finishes are required, e.g. plating.

Cold rolled sizes up to 100mm wide and 7mm thick inclusive are produced by cold rolling to produce flat and some special shape sections to suitable tolerances and surface finishes.

Current Steel-Making Practice

Old Prefix	New Prefix	Practice	Example of Old Prefix	Example of New Prefix
R	U	Steel with unspecified deoxidisation (no minimum % Si specified)	R1008	U1004
S	U		S1010	U1010
CS	M	Merchant quality. Similar to "U" with wider composition range	CS1020	M1020
K	No prefix	As per relevant table in Standard	K1045	1045
X	X	A major deviation in chemical composition from AISI-SAE grades	XK1320	X1320

Carbon steel groups

10xx	Plain carbon steels
11xx	Sulphurised free cutting carbon steels. (Free machining steels)
12xx	Phosphorised and sulphurised free cutting carbon steels
xxLxx	Lead bearing free cutting carbon steels
13xx	Carbon - manganese steels. (Pearlitic manganese steels)

Chemical Composition (specified elemental limits as per AS 1443)

Grade		C	Si	Mn	P	S	Pb
M1020	Min	0.15	-	0.30	-	-	-
	Max	0.25	0.35	0.90	0.050	0.050	-
M1030	Min	0.25	-	0.30	-	-	-
	Max	0.35	0.35	0.90	0.050	0.050	-
1045	Min	0.43	0.10	0.60	-	-	-
	Max	0.50	0.35	0.90	0.040	0.040	-
1214	Min	-	-	0.80	0.04	0.25	-
	Max	0.15	0.10	1.20	0.09	0.35	-
12L14	Min	-	-	0.80	0.04	0.25	0.15
	Max	0.15	0.10	1.20	0.09	0.35	0.35

Typical minimum tensile properties (not guaranteed as these grades are not tensile tested)
Cold Drawn Condition Tensile (MPa)

Grade Up to 16mm incl. Over 16mm to 38mm incl. Over 38mm to 63.5mm incl.

M1020 480 min 460 min 430 min

M1030 560 min 540 min 520 min

1045 690 min 650 min 640 min

1214 480 min 430 min 400 min

12L14 480 min 430 min 400 min

Turned and Polished Condition (Hot Finished) Tensile Strength (MPa)

Grade	Up to 50mm incl.	Over 50mm to 250mm incl.
M1020	480 mim	460 min
M1030	560 min	540 min
1045	690 min	650 min
1214	480 min	430 min
12L14	480 min	430 min

Note that alternative grades with guaranteed mechanical properties are available subject to special order.

Grade Datasheets

Grade	Description
Atlas M1020 Datasheet [171kb]	All purpose low carbon steel with good ductility and weldability. Application in non-critical engineering applications.
Atlas M1030 Datasheet [171kb]	All purpose medium carbon steel with intermediate strength good ductility and weldability. Application in low-stress engineering applications.
Atlas 1214FM Datasheet [172kb]	Low carbon free-machining steel with excellent machinability for non-critical engineering applications.
Atlas 12L14FM Datasheet [172kb]	Low carbon free-machining steel with lead addition. Superior machinability in high-speed machining. Application in non-critical engineering applications. Cannot be welded.

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Bright Mild Steel Bar